This application generally relates to silk screen printing apparatus and more particularly to a novel and improved apparatus for aligning silk screen printing frames on an apparel support platen or shirt board.
There is a proliferation of T-shirt shops in this country and characteristically these shops specialize in custom work wherein a customer will make a specific request for a certain shirt design. It is virtually impossible for the small shops to carry a complete line of shirt designs and accordingly when a customer requests a particular shirt design, rather than to carry all of the shirts in stock, it is desirable to be able to imprint the design on the shirt while the customer waits. More and more, shirt designs are multi-colored but the silk screen equipment designed for such multi-color jobs is quite expensive and beyond the means and budget of most of the smaller shirt shops to carry such equipment and to be able to furnish custom printing services on site. Moreover, the multi-color printing systems now in use are quite bulky and occupy a fair amount of space so as not to be very practical for use in the smaller shops.
A particular problem associated with multi-color printing with silk screens is that the screens cannot be aligned accurately enough to permit successive placement of different screens over the same shirt or other article to perform multi-color jobs. In other words, unless each screen is accurately positioned and aligned with respect to the shirt and the preceding application of one color to the shirt, the different colored inks will tend to bleed or run together.
Of the various efforts made to solve this problem, U.S. Pat. No. 4,708,057 to T. C. Hogenson proposes to employ hinged brackets which clampingly engage a silk screen but is primarily concerned with multi-color wrap-around designs. In order to avoid the problem of accurate realignment between the different color patterns applied in succession to the article, Hogenson employs a printing platen having light-transmitting sections located in those areas where the edges of the article needing alignment will rest on the platen so that by directing light through those sections the operator can more accurately align and register the successive patterns applied.
U.S. Pat. No. 4,679,501 to A. L. Hanosh is also concerned with the problem of registration or proper alignment of the garment with respect to indicia to be printed on the garment, but Hanosh is concerned more with the proper positioning of a transparent sheet with respect to a silk screen.
U.S. Pat. Nos. 3,460,470 and 3,460,471 to M. E. Green et al disclose a method and apparatus for multi-color silk screen printing in which front and side guide pins are provided to establish proper registration of the article. U.S. Pat. No. 4,606,268 to D. Jaffa is directed to a multistation printing device similar to that of Hogenson; and U.S. Pat. No. 4,315,461 to C. W. Harpold uses the combination of hinged clamps and a counterweight to retain the screen in a particular position for multi-color printing. Also, Harpold provides for adjustable positioning of the distance between the print head and platen. Other representative patents are U.S. Pat. Nos. 1,029,544 to G. Horvath; 1,518,863 to A. H. Lutz et al and 2,244,272 to K. B. Vollstorf.
Diamond Chase Company of Huntington Beach, Calif. uses a registration plate which has spaced holes in it mounted to the silk screen in order to align the screen in the frame support clamping jaw. A fixed plate with correspondingly spaced holes is bolted to the shirt board support arm. The silk screen is aligned in the screen support clamping jaw by fitting a removable rod vertically through each set of aligned holes in the registration plate and the fixed plate on the support arm. The clamping jaw is tightened and the rods removed. This arrangement does not prevent side-to-side movement of the pivoting frame support assembly during subsequent printing operations.
A silk screen printing press which provides fixed registration pins to align the frames over the shirt board is disclosed in my U.S. Pat. No. 5,094,161. In order to overcome any binding of the registration pins in the silk screens, lift tabs are employed to engage the silk screen to lift it off the pins as the clamping plate is raised.
Accordingly, there remains a need for an improved assembly which eliminates side-to-side movement of the frame and ensures accurate placement of the frame over the apparel support platen repetitively and consistently without binding. There is also a need for a device which is adaptable for use both with conventional single and multistation presses and which can accommodate frames of different thicknesses and different hole spacings.